Positioning module, optical touch system and method of calculating a coordinate of a touch medium

ABSTRACT

A method of calculating a coordinate of a touch medium is disclosed in the present invention. The method includes obtaining a first image to determine whether the first image overlaps a first threshold, generating a first interceptive boundary when the first image overlaps the first threshold, obtaining a second image to generate a second interceptive boundary by overlap of the second image and a second threshold, determining whether the first interceptive boundary overlaps the second interceptive boundary, and confirming a status of the touch medium according to determination.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. application Ser. No.13/848,720, filed 2013 Mar. 21.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a positioning module, an optical touchsystem and a method of a calculating coordinate of the touch medium, andmore particularly, to a positioning module, an optical touch system anda method of calculating a coordinate of the touch medium that are ableto actuate coordinate calculation when the touch medium contacts a touchpanel.

2. Description of the Prior Art

A light source of the conventional optical touch module is disposedabove the optical detector, the optical shelter path can be effectivewhen an object is put into a projecting range of the light source, andthe optical touch module can calculate the correct position of theobject. However, position of the light source is higher than position ofthe camera of the optical detector. Beam emitted from the light sourceis shadowed by the object before the object contacts the touch plane,and the optical detector is actuated to detect motion of the object whenthe object does not contact the touch plane. As the light source and theoptical detector are disposed on the same perpendicular plane, a darkarea, which is formed when the beam emitted from the light source isshadowed by the object, is deviated because the optical detectormisaligns with an optical path from the light source to the object, sothat the optical detector can not calculate the correct position of theobject according to the captured image. Thus, design of an optical touchsystem capable of actuating the coordinate calculation when the objectcontacts or almost contacts the touch plane for correct position of theobject is an important issue in the optical touch industry.

SUMMARY OF THE INVENTION

The present invention provides a positioning module, an optical touchsystem and a method of calculating coordinates of the touch medium thatcan actuate the coordinate calculation when the touch medium contacts atouching panel for solving above drawbacks.

According to the claimed invention, a method of calculating a coordinateof a touch medium is disclosed. The method includes obtaining a firstimage to determine whether the first image overlaps a first threshold,generating a first interceptive boundary when the first image overlapsthe first threshold, obtaining a second image to generate a secondinterceptive boundary by overlap of the second image and a secondthreshold, determining whether the first interceptive boundary overlapsthe second interceptive boundary, and confirming a status of the touchmedium according to determination.

According to the claimed invention, a positioning module for calculatinga coordinate of a touch medium is disclosed. The positioning moduleincludes at least one image detecting unit and a processor. The imagedetecting unit is adapted to capture a first image generated by a firstbeam emitted from a lateral side of the image detecting unit, and isfurther adapted to capture a second image generated by a second beamemitted from an upper side of the image detecting unit. The processor iselectrically connected to the image detecting unit. The processor isadapted to generate a first interceptive boundary when the first imageoverlaps a first threshold, and to generate a second interceptiveboundary when the second image overlaps a second threshold. Theprocessor further determines whether the first interceptive boundaryoverlaps the second interceptive boundary for confirming a status of thetouch medium according to determination.

According to the claimed invention, an optical touch system forcalculating a coordinate of a touch medium is disclosed. The opticaltouch system includes a panel and a positioning module. The positioningmodule is disposed on the panel. The positioning module includes atleast one image detecting unit and a processor. The image detecting unitis adapted to capture a first image generated by a first beam emittedfrom a lateral side of the image detecting unit, and is further adaptedto capture a second image generated by a second beam emitted from anupper side of the image detecting unit. The processor is electricallyconnected to the image detecting unit. The processor is adapted togenerate a first interceptive boundary when the first image overlaps afirst threshold, and to generate a second interceptive boundary when thesecond image overlaps a second threshold. The processor furtherdetermines whether the first interceptive boundary overlaps the secondinterceptive boundary for confirming a status of the touch mediumaccording to determination.

According to the claimed invention, a positioning module for calculatinga coordinate of a touch medium is disclosed. The positioning moduleincludes at least one image detecting unit and a processor. The imagedetecting unit is adapted to capture a first image generated by a firstbeam emitted from a lateral side of the image detecting unit, and isfurther adapted to capture a second image generated by a second beamemitted from an upper side of the image detecting unit. The processor iselectrically connected to the image detecting unit. The processor drivesthe image detecting unit to capture the first image, and drives theimage detecting unit to capture the second image if the first imageoverlaps a first threshold. The first image is used to determine a firstinterceptive boundary when the first image overlaps the first threshold,and the second image is used to determine a second interceptive boundarywhen the second image overlaps a second threshold. The processor isadapted to determine whether the first interceptive boundary overlapsthe second interceptive boundary and confirm a status of the touchmedium according to determination.

The optical touch system of the present invention can prevent thecoordinate calculation from error because the touch medium does notcontact the panel, and can rapidly acquire the coordinates of the touchmedium relative to the panel for enhancement of the positioning speedand calculating accuracy.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram of an optical touch system according to anembodiment of the present invention.

FIG. 1B is a diagram of the optical touch system according to the otherembodiment of the present invention.

FIG. 2 is a flow chart of calculating the coordinates of a touch mediumaccording to a first embodiment of the present invention.

FIG. 3 is a flow chart of calculating the coordinates of the touchmedium according to a second embodiment of the present invention.

FIG. 4 is a flow chart of calculating the coordinates of the touchmedium according to a third embodiment of the present invention.

FIG. 5 is a comparative diagram of information detected by the imagedetecting unit via the first and second light sources and the secondlight source according to the third embodiment of the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 1A. FIG. 1A is a diagram of an optical touch system10 according to an embodiment of the present invention. A touch medium12 can be utilized to draw a track, and the optical touch system 10 candetect coordinates of the touch medium 12 so as to output thecorresponding operation command according to the coordinate variation.The optical touch system 10 includes a panel 14 and a positioning module16. The touch medium 12 can move on a surface of the panel 14. Thepositioning module 16 is disposed on the panel 14 for calculating thecoordinates of the touch medium 12. Generally, the touch medium 12 canbe user's finger or the stylus.

As shown in FIG. 1A, the positioning module 16 includes at least oneimage detecting unit 18, a first light source 20, a second light source22, a reflection component 24 and a processor 26. The reflectioncomponent 24 is disposed on at least one side of the panel 14. The imagedetecting unit 18, the first light source 20 and the second light source22 are disposed on the other side of the panel 14 relative to thereflection component 24. The first light source 20 is disposed on alateral side 18A (the slash area) of the image detecting unit 18, thesecond light source 22 is disposed on an upper side 18B (the dottedarea) of the image detecting unit 180. The first light source 20 and thesecond light source 22 respectively emit a first beam B1 and a secondbeam B2. The first beam B1 and the second beam B2 are reflected by thereflection component 24 to project on the image detecting unit 18. Theimage detecting unit 18 is adapted to capture a first image generated bythe first beam B1, and is further adapted to capture a second imagegenerated by the second beam B1. A mirror component 28 can be disposedon the side of the panel 14 opposite to the image detecting unit 18, andthe image detecting unit 18 can simultaneously capture a real image anda virtual image of the touch medium 12 for coordinate calculation.

The positioning module 16 can further include a plurality of imagedetecting units 18 respectively disposed on corners or sides of thepanel 14, as shown in FIG. 1B. The light source is disposed on the upperside of each image detecting unit 18. FIG. 1B is a diagram of theoptical touch system 10 according to the other embodiment of the presentinvention. The positioning module 16 can utilize image positions of thetouch medium 12 projected on the image detecting units 18 to calculatethe coordinates by triangulation method. An amount and disposition ofthe image detecting unit 18 is not limited to the above-mentionedembodiment, and depend on design demand.

In addition, the processor 26 is electrically connected to the imagedetecting unit 18. The processor 26 is adapted to generate a firstinterceptive boundary I1-I1′ when the first image overlaps a firstthreshold T1, and further to generate a second interceptive boundaryI2-I2′ when the second image overlaps a second threshold T2, and thenthe processor 26 determines whether the first interceptive boundaryI1-I1′ overlaps the second interceptive boundary I2-I2′, to confirm astatus of the touch medium 12 according to determination. The first beamB1 is shadowed when the touch medium 12 moves into detection range ofthe positioning module 16. A part of the first beam B1 is shadowed togenerate a first dark area on the reflection component 24. The imagedetecting unit 18 can capture the first image with the first dark area.Then, the processor 26 analyzes an intensity of the first dark area onthe first image to determine the touch status of the touch medium 12relative to the panel 14. The first dark area may cover one or morecolumns. A comparing threshold can further be set for determiningwhether the first dark area is generated. For example, the presentinvention can set the comparing threshold as three columns, so that theshadowed image with dimensions smaller than three columns does notbelong to the first dark area.

The processor 26 compares an intensity of the first image to a thresholdvalue, and determined whether the touch medium 12 contacts the panel 14according to a comparison. The intensity of the first image includes aplurality of intensity magnitudes, and each intensity magnitudecorresponds to a typical value of the each column of the first image.The threshold value includes a plurality of threshold magnitudes, andthese threshold magnitudes respectively correspond to intensitythresholds of a plurality of columns of the first image. When theintensity magnitude of one column of the first image is lower than thecorresponding intensity thresholds, the column can be within the firstdark area of the first image. The processor 26 can determine that thetouch medium 12 has contacted the panel 14 according to the intensitymagnitude of the first dark area.

The processor 26 further can determine a touch position of the touchmedium 12 on the panel 14 according to the second image captured by theimage detecting unit 18. When the touch medium 12 is put on the panel14, a part of the second beam B2 is shadowed by the touch medium 12, anda second dark area is formed on the reflection component 24. Then, theprocessor 26 can compare a plurality of intensity magnitudes of thesecond image to the at least one threshold value, so as to find out theimaging position of the second dark area on the second image, and todetermine the touch position of the touch medium 12 on the panel 14(which means the coordinates of the touch medium 12 can be calculated).The second dark area may cover one or more columns. A comparingthreshold can further be set for determining whether the second darkarea is generated. For example, the present invention can set thecomparing threshold as three columns, so that the shadowed image withdimensions smaller than three columns does not belong to the second darkarea.

As shown in FIG. 1A, the first light source 20 is disposed on thelateral side 18A, the second light source 22 is disposed on the upperside 18B, so that a distance between the first light source 20 and thesurface of the panel 14 (the plane where the touch medium 12 moves) issubstantially smaller than a distance between the second light source 22and the surface of the panel 14. Regards to the panel 14, the firstlight source 20 shares the same vertical position with the imagedetecting unit 18, and the second light source 22 shares the samehorizontal position with the image detecting unit 18. When the touchmedium 12 moves into the detection range of the positioning module 16,the processor 26 drives the image detecting unit 18 to capture the firstimage, and determines the touch status according to the intensity of thefirst dark area on the first image. As the touch medium 12 contacts thepanel 14 (or a distance between the touch medium 12 and the panel 14 issmaller than a predetermined value), the processor 26 can start theanalysis of the second image, so as to calculate the touch position (thecoordinates) of the touch medium 12 on the panel 14.

It should be mentioned that the processor 26 can be electricallyconnected to the first light source 20 and the second light source 22,selectively. The processor 26 can respectively actuate the imagedetecting unit 18, the first light source 20 and the second light source22. The image detecting unit 18 is actuated to respectively capture thefirst image and the second image, and the processor 26 can analyze thefirst image and the second image to determine the touch status and thetouch position. For energy consumption of the positioning module 16, theprocessor 26 can control the first light source 20 and the second lightsource 22 to respectively output the first beam B1 and the second beamB2. Emitting period of the first light source 20 and the second lightsource 22 can be different. As the positioning module 16 includes theplurality of image detecting units 18, the first light source 20 and thesecond light source 22 can simultaneously or respectively emit thebeams. In a power saving mode, the processor 26 can actuate the firstlight source 20 to generate the first image, analyze the first image,shut down the first light source 20 when the touch medium 12 contactsthe panel 14, and then actuate the second light source 22 to generatethe second image. Therefore, the present invention not only caneffectively calculate the correct touch position of the touch medium 12on the panel 14, but also can economize the energy of the light sources.

Please refer to FIG. 2. FIG. 2 is a flow chart of calculating thecoordinates of the touch medium 12 according to a first embodiment ofthe present invention. The method of calculating the coordinates of thetouch medium 12 shown in FIG. 2 is applied to the optical touch system10 shown in FIG. 1A. First, step 200 is executed to initialize theoptical touch system 10. Then, step 202 is executed to actuate the firstlight source 20. The first light source 20 emits the first beam B1, andthe first beam B1 is reflected by the reflection component 24 to projectthe first image on the image detecting unit 18. Then, step 204 isexecuted to determine the touch status of the touch medium 12. When thetouch medium 12 is put on the panel 14, a part of the first beam B1 isshadowed by the touch medium 12 to generate the first dark area, so thefirst image captured by the image detecting unit 18 has the first darkarea. The processor 26 can compare the intensity of the first dark areaon the first image to the threshold value, and determine whether thetouch medium 12 contacts the panel 14. As the intensity is greater thanthe threshold value, the touch medium 12 does not contact the panel 14and step 202 is executed. As the intensity is smaller than the thresholdvalue, the touch medium 12 contacts the panel 14, and step 206 isexecuted to actuate the second light source 22. Meanwhile, the firstlight source 20 can be selectively shut down for the energy economy.

The second light source 22 can emit the second beam B2. The second beamB2 is reflected by the reflection component 24 to project the secondimage on the image detecting unit 18. Because the touch medium 12 is puton the panel 14, the part of the second beam B2 is shadowed by the touchmedium 12 to generate the second dark area. Then, step 208 is executedto calculate the position of the touch medium 12. The processor 26 cancalculate the touch position (the coordinates) of the touch medium 12 onthe panel 14 according to the position of the second dark area on thesecond image. Step 210 is executed to output the coordinates of thetouch medium 12 on the panel 14 by the processor 26, so as to be thecontrol command to execute the corresponding application program.Meanwhile, the second light source 22 can be shut down. After output ofthe coordinates, the positioning module 16 finishes the touch detection,and step 202 is executed again to actuate the first light source 20 fordriving the image detecting unit 18 to capture the first image, and todrive the processor 26 to determine the touch status of the touch medium12 at next phase according to the first image.

Please refer to FIG. 3. FIG. 3 is a flow chart of calculating thecoordinates of the touch medium 12 according to a second embodiment ofthe present invention. The method of calculating the coordinates of thetouch medium 12 shown in FIG. 3 is applied to the optical touch system10 shown in FIG. 1A. Steps 300-310 for calculating the coordinates ofthe touch medium 12 in the second embodiment are substantially the sameas steps 200-210 mentioned in the first embodiment. The other powersaving mode is disclosed in the second embodiment. Difference betweenthe second embodiment and the first embodiment is that method in thesecond embodiment can execute step 312 after the coordinates of thetouch medium 12 is outputted, so as to determine whether the touchmedium 12 is spaced from the panel 14. As the touch medium 12 is notspaced from the panel 14, the image detecting unit 18 can capture thesecond image for the second time, and the processor 26 can analyze theimaging position of the second dark area to calculate the touch positionof the touch medium 12 at the next phase. As the touch medium 12 isspaced from the panel 14, the processor 26 can shut down the secondlight source 22 and actuate the first light source 20, and drive theimage detecting unit 18 to capture the first image. The processor 26 cananalyze the first dark area on the captured first image to determine thetouch status of the touch medium 12 at the next phase.

For the energy economy, step 312 is the second embodiment discloses thatthe processor 26 compares the intensity of the second image to thethreshold value. When the intensity are greater than the correspondingthreshold value, the second dark area is disappeared, which means thetouch medium 12 is spaced from the panel 14, so that step 302 isexecuted to actuate detection of the touch status of the touch medium12. When at least one of the intensity is lower than the correspondingthreshold value, the second dark area exists because the second beam B2is shadowed by the touch medium 12, which means the touch medium 12 iswithin the detection range of the positioning module 16, and the touchmedium 12 is not spaced from the panel 14, so that step 308 is executedto calculate the touch position of the touch medium 12 at the nextphase.

Please refer to FIG. 4 and FIG. 5. FIG. 4 is a flow chart of calculatingthe coordinates of the touch medium 12 according to a third embodimentof the present invention. FIG. 5 is a comparative diagram of informationdetected by the image detecting unit 18 via the first light source 20and the second light source 22 according to the third embodiment of thepresent invention. The method illustrated in FIG. 4 especially focuseson procedures of determining the status of the touch medium 12 bycomparison of the image intensity and the predetermined threshold.Before formal detection, step 500 is executed to obtain a firstbackground image and a second background image and respectively to set afirst threshold and a second threshold. The image detecting unit 18obtains the first background image by the first light source 20, andobtains the second background image by the second light source 22. Theprocessor 26 receives raw images of the first background image and thesecond background image, and then transforms the raw images intocorresponding profiles BG1 and BG2, as shown in FIG. 5. The thresholdcan be determined in several ways, such as being proportional to theprofile of the background image. The first threshold T1 and the secondthreshold T2 can respectively be different percentages of the profilesof the first background image BG1 and the second background image BG2,and the first threshold T1 is substantially smaller than the secondthreshold T2.

As the optical touch system 10 is started, step 502 is executed toobtain the second image for initial inspection by determining whetherthe second image overlaps the second threshold T2. The processor 26 cantransform a raw image (n*m pixels, n and m are respectively greater thanone) into a profile (n*1 pixels, n is greater than one), and utilizesthe profile to compare with the threshold. It should be mentioned theprocessor 26 calculates a specific value of the profile, the specificvalue can be an average level or a minimal level etc., and the processor26 compares the profile with the threshold by determining whether thespecific value is lower than the threshold. The touch medium 12 is at ahovering status when the second image (not shown in figures) does notoverlap the second threshold T2, and step 504 is executed that theprocessor 26 determines the coordinate calculation is not actuated. Step506 is executed to obtain the average level or the minimal level of thefirst image when the second image (such as the signature C21, C22)overlaps the second threshold T2. The second image overlaps the secondthreshold T2 does not mean the touch medium 12 directly contacts thepanel 14, so that the method of the present invention continuouslyutilizes the first light source 20 to detect the correct status of thetouch medium 12.

After the image detecting unit 18 obtains the first image, step 508 isexecuted to determine whether the first image overlaps the firstthreshold T1. The touch medium 12 hovers above the panel 14 when theprofile of the first image (such as the signature C11) does not overlapthe first threshold T1; in the meantime, though the profile of thesecond image C21 overlaps the second threshold T2, step 510 is executedto determine the touch medium 12 is at the hovering status by theprocessor 26. Further, the touch medium 12 contacts the panel 14 whenthe profile of the first image (such as the signature C12) overlaps thefirst threshold T1, and step 512 is executed to generate the firstinterceptive boundary I1-I1′, and the second interceptive boundaryI2-I2′ is accordingly generated by overlap of the second image C22 andthe second threshold T2. Generally, the second image C22 overlaps thesecond threshold T2 while the first image C12 overlaps the firstthreshold T1 because the second threshold T2 is greater than the firstthreshold T1.

The optical touch system 10 of the present invention provides a multipletouch function, and the method applied to the optical touch system 10can distinguish whether the detected first image and the related secondimages belong to the same touch medium 12 or not. Step 514 is executedto determine whether the first interceptive boundary I1-I1′ overlaps thesecond interceptive boundary I2-I2′, so as to confirm the status of thetouch medium 12 according to above-mentioned determination. When thefirst interceptive boundary I1-I1′ does not overlap the secondinterceptive boundary I2-I2′, the first image C12 and the second imageC22 maybe generated according to different touch media 12, more than onetouch medium 12 located above the panel 14, and step 516 is executed toconfirm the touch medium 12 is at the hovering status. When the firstinterceptive boundary I1-I1′ overlaps the second interceptive boundaryI2-I2′, the dark areas projected on the first image C12 and the secondimage C22 represent the same touch medium 12, step 518 is executed toconfirm the touch medium 12 is at a touch status, and the touch positionis calculated according to the second image C22 by the processor 26.

In the first embodiment, the processor 26 actuates the detection of thetouch status of the touch medium 12 after the processor 26 outputs thetouch position of the touch medium 12, so as to calculate allcoordinates of the touch medium 12 when the touch medium 12 movesthrough the panel 12. The processor 26 repeatedly actuates the detectionof the touch status of the touch medium 12 regardless of position of thetouch medium 12 relative to the positioning module 16 (the touch medium12 may be inside or outside the detection range of the positioningmodule 16), so as to ensure that the positioning module 16 can catchevery position of the touch medium 12 when the touch medium 12 movesover the panel 12. In the second embodiment, the processor 26 candetermine whether the touch medium 12 is spaced from the panel 12 afterthe processor 26 outputs the last touch position of the touch medium 12.As the touch medium 12 is not spaced from the panel 14, the positioningmodule 16 can utilize the processor 26 to immediately analyze the secondimage captured by the image detecting unit 18, so as to calculate thetouch position of the touch medium 12 at the present phase. Therefore,the optical touch system 10 of the present invention can utilize themethod shown in FIG. 2 to increase calculation speed of the coordinatedetection and to economize the energy consumption of the first lightsource 20.

The third embodiment details the method of distinguishing the touchmedium 12 into different statuses. The processor 26 sets the firstthreshold T1 and the second threshold T2 by different percentages. Thetouch medium 12 is at the hovering status when the first image C11 doesnot overlap the first threshold T1 regardless of the overlap between thesecond image C21, C22 and the second threshold T2. For example, as theprocessor 26 drives the image detecting unit 18 to capture the firstimage, the image detecting unit 18 is driven to capture the second imageC22 when the first image C12 overlaps the first threshold T1, or theimage detecting unit 18 does not capture the second image C21 becausethe first image C11 does not overlap the first threshold T1. The touchmedium 12 is at the hovering status even through the first image C12overlaps the first threshold T1 and the first interceptive boundaryI1-I1′ does not overlap the second interceptive boundary I2-I2′. It isto say, the touch medium 12 is at the touch status when the first imageC12 overlaps the first threshold T1, the first interceptive boundaryI1-I1′ overlaps the second interceptive boundary I2-I2′, and the secondimage C22 overlaps the second threshold T2 certainly. For the abovereason, the method illustrated in the third embodiment can accuratelymake out the status of the touch medium, so as to determine whether theoptical touch system 10 is switched to the power saving mode (when thetouch medium is at the hovering status) or the coordinate detecting mode(when the touch medium is at the touch status).

In conclusion, the optical touch system of the present inventionutilizes the two light sources disposed on different positions, so thatthe positioning module can detect whether the touch medium contacts thepanel in advance, and then execute the coordinate calculation when thetouch medium has contacted the panel. The present invention not only cancalculate the correct coordinates of the touch medium on the panel, butalso can economize the energy of light sources. The first light sourcedisposed on the lateral side of the image detecting unit can generatethe first dark area when the touch medium contacts the panel. Thepositioning module compares the intensity of the first dark area to thethreshold value, and determines the touch status of the touch mediumrelative to the panel. The second light source disposed on the upperside of the image detecting unit can be actuated after the touch mediumcontacts the panel, and the positioning module can calculate the touchposition of the touch medium on the panel accurately. Thus, the opticaltouch system of the present invention can prevent the coordinatecalculation from error because the touch medium does not contact thepanel, and can rapidly acquire the coordinates of the touch mediumrelative to the panel for enhancement of the positioning speed andcalculating accuracy.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A method of calculating a coordinate of a touchmedium, the method comprising: obtaining a first image to determinewhether the first image overlaps a first threshold; generating a firstinterceptive boundary when the first image overlaps the first threshold;obtaining a second image to generate a second interceptive boundary byoverlap of the second image and a second threshold; determining whetherthe first interceptive boundary overlaps the second interceptiveboundary; and confirming a status of the touch medium according todetermination.
 2. The method of claim 1, wherein the method ofconfirming the status of the touch medium further comprises: confirmingthe touch medium is at a hovering status when the first interceptiveboundary does not overlap the second interceptive boundary.
 3. Themethod of claim 1, wherein the method of confirming the status of thetouch medium further comprises: confirming the touch medium is at atouch status when the first interceptive boundary overlaps the secondinterceptive boundary; and calculating a touch position of the touchmedium according to the second image.
 4. The method of claim 1, furthercomprising: obtaining a first background image and a second backgroundimage to respectively set the first threshold and the second threshold.5. The method of claim 4, wherein the first threshold is a percentage ofthe first background image, the second threshold is another percentageof the second background image, and the first threshold is substantiallysmaller than the second threshold.
 6. The method of claim 1, wherein themethod of obtaining the first image to determine whether the first imageoverlaps the first threshold further comprises: receiving a raw image ofthe first image; transforming the raw image into a profile; andutilizing the profile of the first image to compare with the firstthreshold.
 7. The method of claim 6, wherein the method of utilizing theprofile of the first image to compare with the first threshold furthercomprises: calculating a specific value of the profile; and determiningwhether the specific value is lower than the first threshold, whereinthe specific value is an average level or a minimal level.
 8. The methodof claim 1, wherein the first image is captured by an image detectingunit according to a first beam emitted from a first light source, thesecond image is captured by the image detecting unit according to asecond beam emitted from a second light source, the first light sourceand the second light source are respectively disposed on a lateral sideand an upper side of the image detecting unit.
 9. A positioning modulefor calculating a coordinate of a touch medium, the positioning modulecomprises: at least one image detecting unit, the image detecting unitbeing adapted to capture a first image generated by a first beam emittedfrom a lateral side of the image detecting unit, and further beingadapted to capture a second image generated by a second beam emittedfrom an upper side of the image detecting unit; and a processorelectrically connected to the image detecting unit, the processor beingadapted to generate a first interceptive boundary when the first imageoverlaps a first threshold, and to generate a second interceptiveboundary when the second image overlaps a second threshold, anddetermining whether the first interceptive boundary overlaps the secondinterceptive boundary for confirming a status of the touch mediumaccording to determination.
 10. The positioning module of claim 9,wherein the image detecting unit detects a first dark area because apart of the first beam is shadowed by the touch medium, and theprocessor determines the status according to an intensity of the firstdark area on the first image.
 11. The positioning module of claim 9,wherein the processor confirms the touch medium is at a hovering statuswhen the first interceptive boundary does not overlap the secondinterceptive boundary.
 12. The positioning module of claim 9, whereinthe processor confirms the touch medium is at a touch status when thefirst interceptive boundary overlaps the second interceptive boundary,and calculates a touch position of the touch medium according to thesecond image.
 13. The positioning module of claim 9, wherein theprocessor drives the image detecting unit to obtain a first backgroundimage and a second background image to respectively set the firstthreshold and the second threshold, the first threshold is substantiallysmaller than the second threshold.
 14. The positioning module of claim9, wherein the processor drives the image detecting unit to receive araw image of the first image, transforms the raw image into a profile,and compares the profile of the first image with the first threshold.15. The positioning module of claim 14, wherein the processor calculatesa specific value of the profile to determine whether the specific islower than the first threshold, and the specific value is an averagelevel or a minimal level.
 16. The positioning module of claim 9, whereinthe processor generates the second interceptive boundary and obtains thefirst image when the second image overlaps the second threshold.
 17. Anoptical touch system for calculating a coordinate of a touch medium, theoptical touch system comprising: a panel; and a positioning moduledisposed on the panel, the positioning module comprising: at least oneimage detecting unit, the image detecting unit being adapted to capturea first image generated by a first beam emitted from a lateral side ofthe image detecting unit, and further being adapted to capture a secondimage generated by a second beam emitted from an upper side of the imagedetecting unit; and a processor electrically connected to the imagedetecting unit, the processor being adapted to generate a firstinterceptive boundary when the first image overlaps a first threshold,and to generate a second interceptive boundary when the second imageoverlaps a second threshold, and determining whether the firstinterceptive boundary overlaps the second interceptive boundary forconfirming a status of the touch medium according to determination. 18.The optical touch system of claim 17, wherein the image detecting unitdetects a first dark area because a part of the first beam is shadowedby the touch medium, and the processor determines the status accordingto an intensity of the first dark area on the first image.
 19. Theoptical touch system of claim 17, wherein the processor confirms thetouch medium is at a hovering status when the first interceptiveboundary does not overlap the second interceptive boundary.
 20. Theoptical touch system of claim 17, wherein the processor confirms thetouch medium is at a touch status when the first interceptive boundaryoverlaps the second interceptive boundary, and calculates a touchposition of the touch medium according to the second image.
 21. Theoptical touch system of claim 17, wherein the processor drives the imagedetecting unit to obtain a first background image and a secondbackground image to respectively set the first threshold and the secondthreshold, the first threshold is substantially smaller than the secondthreshold.
 22. The optical touch system of claim 17, wherein theprocessor drives the image detecting unit to receive a raw image of thefirst image, transforms the raw image into a profile, and compares theprofile of the first image with the first threshold.
 23. The opticaltouch system of claim 22, wherein the processor calculates a specificvalue of the profile to determine whether the specific is lower than thefirst threshold, and the specific value is an average level or a minimallevel.
 24. The optical touch system of claim 17, wherein the processorgenerates the second interceptive boundary and obtains the first imagewhen the second image overlaps the second threshold.
 25. A positioningmodule for calculating a coordinate of a touch medium, the positioningmodule comprises: at least one image detecting unit, the image detectingunit being adapted to capture a first image generated by a first beamemitted from a lateral side of the image detecting unit, and furtherbeing adapted to capture a second image generated by a second beamemitted from an upper side of the image detecting unit; and a processorelectrically connected to the image detecting unit, the processordriving the image detecting unit to capture the first image, and drivingthe image detecting unit to capture the second image if the first imageoverlaps a first threshold; wherein the first image is used to determinea first interceptive boundary when the first image overlaps the firstthreshold, and the second image is used to determine a secondinterceptive boundary when the second image overlaps a second threshold;wherein the processor is adapted to determine whether the firstinterceptive boundary overlaps the second interceptive boundary andconfirm a status of the touch medium according to determination.